Examples of techniques concerning substance production using yeast are mainly methods for designing substance production pathways using acetyl-CoA as an intermediate. For example, oleic acid, which is a typical fatty acid, requires 9 molecules of acetyl-CoA as a raw material, and carotin, which is a typical diterpene, requires 12 molecules of acetyl-CoA as a raw material. Accordingly, a technique for synthesizing fatty acid useful as a pharmaceutical product or a fine chemical (Patent Document 1), a technique for synthesizing terpenoid (Patent Document 2), and a technique for synthesizing polyketide (Patent Document 3) using acetyl-CoA accumulated within yeast are known. Furthermore, examples of a substance that is synthesized using acetyl-CoA as an intermediate include butanol (Patent Document 4), isopropanol (Patent Document 5) and farnesene (Patent Document 5), which are attracting attention as biofuels.
In yeast, ethanol produced extracellularly is taken up by cells and then acetyl-CoA is synthesized from the incorporated ethanol. When the concentration of ethanol produced by yeast becomes high, the yeast's own growth is inhibited. Therefore, it has been difficult to increase the amount of acetyl-CoA within cells by means such as a means of increasing the ethanol production capacity of yeast or a means of increasing the amount of ethanol to be taken up by yeast.
More specifically, Patent Document 2 discloses a technique for synthesizing farnesene from acetyl-CoA, but the yield thereof is about 25% of the theoretical yield. Moreover, Patent Document 6 discloses a technique for synthesizing 6-methyl salicylate from acetyl-CoA, but the yield is about 20% of the theoretical yield. As described above, substance production from acetyl-CoA is problematic in that productivity is significantly low.